The subject matter described herein relates generally to magnetic flow meters.
Magnetic flow meters are used to measure the flow of charge-carrier laden fluids, for example water, through a conduit or pipeline. Such flow meters measure the velocity of the fluid moving through the pipeline by using Faraday's Law. Faraday's Law states that a conductor moving through a magnetic field produces a voltage. In this case, the charge-carrier laden fluid acts as a conductor moving though the magnetic field produced by the sensor, thus producing a voltage. The magnitude of the voltage is proportional to the velocity at which the fluid water moves through the magnetic field.
Conventional insertion-type electromagnetic flow meters include electromagnetic coils inside a sensor that produce magnetic fields, and electrodes on the sensor that measure the voltage generated by a fluid moving through those magnetic fields. The planes of the magnetic fields are typically oriented transverse to the flow of fluid so that as conductive fluid passes through the magnetic fields, it induces a voltage measurable by the sensor. Insertion-type electromagnetic flow meters typically include pairs of electrodes that are spaced apart from each other and in electrical contact with the fluid to measure the induced voltage. The measured voltage is used to determine the average velocity of the fluid flowing through the conduit.
Most flow meters thus include a sensor insert or sensor assembly including a magnetic source and one or more sets of electrodes. The sensor assembly is positioned so that the electrodes are in contact with the fluid flowing through the conduit. To obtain an accurate velocity measurement, it is necessary to maintain a magnetic field within the measured region between the electrodes.
Existing flow meters include a body or external component (external to the conduit) and a sensor insert extending into the fluid column perpendicular to the fluid flow. Flow meters incorporate sensing electrodes into the sensor insert, one end of which extends into the fluid and an opposing end extends at least partially into the external body where wiring connected to the electrodes communicates to the external body. The sensor insert may have an interior space therein that includes the magnetic coils to produce the magnetic fields. Appropriate signals from the sensor are provided to meter circuitry to produce flow rate estimates.